CN112875857A

CN112875857A - Denitrification filter material and preparation method and application thereof

Info

Publication number: CN112875857A
Application number: CN202110094665.3A
Authority: CN
Inventors: 何岩; 王鹏程; 陈哲洋
Original assignee: East China Normal University
Current assignee: East China Normal University
Priority date: 2021-01-25
Filing date: 2021-01-25
Publication date: 2021-06-01
Anticipated expiration: 2041-01-25
Also published as: CN112875857B

Abstract

The invention discloses a preparation method of a denitrification filter material, which comprises the steps of cleaning bagasse as a raw material with deionized water, drying in the air, uniformly mixing with siderite and ordinary portland cement according to a certain mass ratio to obtain a mixed material, adding water into the mixed material, uniformly mixing, granulating into a spherical shape, and drying in the air at room temperature to obtain the denitrification filter material. The denitrification filter material is an organic matter-ferrous matrix composite system, is based on a mixed nutrition type denitrification mode, can realize high-efficiency denitrification of the tail water of the sewage plant without an external carbon source, has the advantages of low cost, simple preparation, good hydraulic performance and the like, can be applied to deep denitrification of the tail water of the sewage plant, can also be used for denitrification of wastewater with low C/N ratio, simultaneously provides a brand-new way for resource utilization of bagasse, and achieves the aim of treating waste with waste.

Description

Denitrification filter material and preparation method and application thereof

Technical Field

The invention belongs to the field of sewage treatment and the technical fields of ecology and environment, relates to a preparation method and application of a denitrification filter material, and particularly relates to a denitrification filter material for efficiently denitrifying tail water of a municipal sewage plant, and a preparation method and application thereof.

Background

The healthy water environment is an important component of urban sustainable development. Since the official promulgation of the action plan for preventing and treating water pollution in 2015, the requirements for the discharge standard of urban sewage plants are increasingly strict, and particularly, the requirements for implementing the strict special discharge limit of pollutants in the sewage plants in key drainage basin areas are more strict, wherein how to meet the discharge standard of Total Nitrogen (TN) in sewage under the high discharge standard becomes a hot spot and a difficult point of concern in the field of water treatment. The main nitrogen form in the tail water (secondary effluent) of a sewage treatment plant is nitrate nitrogen, and a denitrification filter tank is the most common deep denitrification process at present. After the sewage is subjected to the whole biological treatment process, tail water almost has no carbon source available for the traditional denitrification, so a large amount of organic carbon sources (sodium acetate, glacial acetic acid and the like) are usually added into the denitrification filter to meet the denitrification requirement. However, the external addition of carbon sources not only greatly increases the operating cost, but also increases the complexity of the operation and maintenance.

As a core part of the denitrification filter tank, the development and the modification of filter materials are concerned by more and more researchers. At present, the research and development of the denitrification filter material mainly focuses on two aspects: one is the optimization of the material, the particle size and the configuration of a filter material based on the improvement of the hydraulic characteristic of the filter, and the currently adopted filter material mainly comprises quartz sand, ceramsite, volcanic rock and the like; on the other hand, the development of the filter material for the reinforced autotrophic denitrification process without carbon source mainly comprises the research and development of the filter material taking sulfur, zero-valent iron or ferrous iron as an electron donor, such as a filter material (CN 201410063868.6) compounded with pyrite + limestone (3-10: 1) (CN 201010524339.3), compounded with siderite (80-95%) + binder (5-15%) + pore-forming agent (0-5%), a filter material (CN 201410063868.6) compounded with 40% of sulfur powder + 20% of sponge iron powder + 40% of silicate cement (CN 201610515192.9), a high-temperature sintered iron-carbon material (iron: carbon ═ 5:1) + 90% of ceramsite (CN 201711322067.7), pyrite + sulfur + siderite (3-12: 3: 1-3) (CN 201710636570.3), fine iron powder (30-60%) + fine carbon powder (40-70%) + ceramsite (1.0-1.2 m) (CN201911395. X) and zeolite + nano ferroferric oxide (CN 202010645880.3). However, the filter materials developed based on the autotrophic nitrogen removal process alone have the problems of low nitrogen removal efficiency, increased sulfate in effluent and the like.

Disclosure of Invention

In order to solve the defects and defects of the existing denitrification filter material, the invention aims to provide a preparation method and application of a novel denitrification filter material based on a mixed nutrition type denitrification mode (heterotrophic denitrification-ferrous anoxic denitrification).

In addition, the material has the advantages of low cost, simple preparation, no need of external carbon source addition, good hydraulic performance, excellent denitrification effect and the like, can be used as a denitrification filter material for deep denitrification of tail water of a sewage plant, and simultaneously provides a novel approach for resource utilization of bagasse.

The invention provides a novel denitrification filter material, which is characterized in that an organic matter-ferrous matrix composite system is prepared by compounding bagasse, siderite and ordinary portland cement serving as raw materials.

Wherein, the mass fractions of bagasse, siderite and ordinary portland cement in the denitrification filter material are respectively 30-40%, 50-70% and 10-15%; preferably, the mass fractions of the bagasse, the siderite and the ordinary portland cement are 40%, 50% and 10%, respectively.

Wherein the bagasse is a byproduct of a sucrose production plant, is cleaned by deionized water, is naturally air-dried at room temperature, is crushed and is sieved by a 100-mesh sieve;

the siderite is common iron ore and is selected from mining areas of Bijie city, Guizhou province, and the siderite is sieved by a 40-mesh sieve after being crushed;

the portland cement is common ordinary portland cement.

The denitrification filter materials existing in the prior art mainly comprise two types: 1) filter materials (quartz sand, ceramsite, volcanic rock and the like) taking heterotrophic denitrification as a main denitrification way usually need to be added with a large amount of carbon sources to maintain the denitrification function; 2) the filter material (iron-based and sulfur-based material, etc.) with autotrophic denitrification as the main denitrification path often has the technical bottleneck of low denitrification efficiency. The denitrification filter material developed by the invention is an organic matter-ferrous matrix composite system, organic matters not only can provide a carbon source for heterotrophic denitrification, but also can provide a carbon source and an energy source for the growth of iron matrix denitrifying bacteria, and can promote electron transfer between ferrous and nitrate.

The invention also provides a preparation method of the denitrification filter material, which comprises the following specific steps:

uniformly mixing bagasse, siderite and ordinary portland cement according to a certain mass ratio to obtain a mixed material, adding water into the mixed material, uniformly mixing, granulating into balls, and then air-drying to obtain the denitrification filter material.

The bagasse is a by-product of a sucrose production plant.

The bagasse also comprises a pretreatment step before use: washing with deionized water, naturally drying at room temperature, crushing, sieving, and sieving.

The siderite is common iron ore and is sieved by a 40-mesh screen after being crushed before use.

The bagasse, the siderite and the ordinary portland cement are in the mass ratio: 30% -40%: 50% -70%: 10% -15%; preferably, it is 40%: 50%: 10 percent.

The mass ratio of the water to the mixed materials is (60-100): 100, respectively; preferably, it is 4: 5.

The diameter d of the sphere is 80 +/-20 mm.

The air drying is preferably carried out at room temperature.

The air drying time is 5-7 days; preferably, it is 7 days.

In one embodiment, the method comprises the following specific steps:

1) selection and pretreatment of raw materials

Bagasse is a byproduct of a sucrose production plant, is cleaned by deionized water, is naturally dried at room temperature, is crushed and is sieved by a 100-mesh sieve; the siderite is common iron ore, and is sieved by a 40-mesh screen after being crushed; portland cement is common ordinary Portland cement.

2) Raw material compounding

The raw materials are uniformly mixed according to the mass fractions of bagasse, siderite and ordinary portland cement of 30-40%, 50-70% and 10-15% respectively to obtain a mixed material, then water is added into the mixed material according to the mass ratio of 80g of water to 100g of the mixed material, the mixture is fully stirred uniformly and granulated into a sphere (the diameter d of the sphere is 80 +/-20 mm). And (3) placing the formed filter material in a ventilation place, and airing for 5-7 days at room temperature. And obtaining the denitrification filter material.

According to the invention, different compounding experiments are carried out to obtain an optimized proportioning range, batch experiments with bagasse mass fractions of 10%, 20%, 30%, 40% and 50% are respectively carried out, 40% -80% of siderite and 10% -20% of ordinary portland cement are simultaneously added, and finally the performance of the mixture is evaluated to obtain the optimized compounding ratio of different raw materials.

The invention also provides the application of the denitrification filter material in deep denitrification of tail water of a sewage plant or denitrification of wastewater with low C/N ratio.

The wastewater with the low C/N ratio is wastewater with the C/N less than 3.

The invention develops a novel denitrification filter material by combining the current research situation at home and abroad and considering the actual requirement of upgrading and modifying deep denitrification in sewage plants in China. The beneficial effects are as follows: the denitrification filter material is an organic matter-ferrous matrix composite system, organic matters not only can provide a carbon source for heterotrophic denitrification, but also can provide a carbon source and an energy source for the growth of iron matrix denitrifying bacteria, and can promote electron transfer between ferrous iron and nitrate.

Drawings

FIG. 1 is a process flow of the denitrification filter material developed by the present invention.

FIG. 2 Denitrification Performance of denitrification Filter (a) and internal Release of Ammonia Nitrogen and COD (b)

FIG. 3 is a graph based on the comparison of denitrification performance of ceramsite and self-made filter material denitrification columns under different hydraulic retention time.

Detailed Description

The present invention will be described in further detail with reference to the following examples and the accompanying drawings. The procedures, conditions, experimental methods and the like for carrying out the present invention are general knowledge and common general knowledge in the art except for the contents specifically mentioned below, and the present invention is not particularly limited.

Example 1 optimized compounding experiment of different raw materials of denitrification filter material

According to the invention, different compounding experiments are carried out to obtain the optimized proportioning range of the raw materials, batch experiments with bagasse mass fractions of 10%, 20%, 30%, 40% and 50% are respectively carried out, 40% -80% of siderite and 10% -20% of ordinary portland cement are simultaneously added, and finally the performance of the materials is evaluated to obtain the optimized compounding ratio of different raw materials. Table 1 summarizes the denitrification performance under different formulation ratio conditions.

TABLE 1 Total nitrogen removal of filter media prepared at different material ratios

Application example 1:

50g of the denitrification filter material prepared according to the formula 7 of the invention in example 1 was placed in a 500mL Erlenmeyer flask and 250mL of simulated wastewater treatment plant tail water (nitrate nitrogen formulated with potassium nitrate, about 12mg/L) was added. Placing the conical flask after plugging in a constant temperature shaking table (25 ℃, 100r/min) for continuous oscillation for 3 days, changing water once and replenishing fresh simulated tail water again; then continuously oscillating for 3 days, changing water and replenishing fresh simulation tail water again; then changing water once a day and detecting the quality of the effluent (figure 1) to judge the denitrification performance of the prepared denitrification filter material. After the system is stable, the total nitrogen removal rate is higher than 80%, the ammonia nitrogen concentration in effluent is lower than 0.5mg/L, and the COD concentration is lower than 20 mg/L.

Application example 2:

the denitrification filter material prepared according to the formula 7 in the embodiment 1 of the invention is filled in a self-made denitrification column (the diameter is 20cm, the height is 120cm) and compared with a control group (ceramsite is used as the filter material) to verify the denitrification effect of the filter material. The denitrification column adopts an up-flow type operation mode, and water enters from bottom to top to sequentially pass through a water distribution area (5cm), a pebble supporting layer (15cm), a filter material layer (100cm) and a super-high layer (30 cm). The tail water of the simulated sewage plant is circulated in the denitrification column for 8 days through the peristaltic pump, and fresh simulated tail water is supplemented to maintain the nitrate nitrogen concentration in the period, so that the microorganisms are promoted to form a film on the surface and in the interior of the filter material. Then, normal water inflow is started, and the denitrification effects of the filter material and the ceramsite prepared under different hydraulic retention times are compared (figure 2). The denitrification efficiency of the denitrification filter is relatively best (the total nitrogen removal rate is more than 80%) under the condition that the Hydraulic Retention Time (HRT) is 5 h.

The above examples can show that the denitrification filter material developed in the invention can realize the high-efficiency denitrification of the tail water of the sewage plant by more than 80% without an external carbon source (the denitrification removal rate of the denitrification filter material is about 80% under the condition of externally increasing the amount of the carbon source in the existing common technology), and the whole manufacturing process of the filter material is simple, the raw materials are cheap, and a novel approach is provided for the resource utilization of bagasse.

The above-described embodiments of the present invention are not intended to be limiting. Variations and advantages that may occur to those skilled in the art may be incorporated into the invention without departing from the spirit and scope of the inventive concept.

Claims

1. A denitrification filter material is characterized in that the denitrification filter material is an organic matter-ferrous matrix composite system, and is prepared by compounding bagasse, siderite and ordinary portland cement as raw materials; the mass fractions of bagasse, siderite and ordinary portland cement in the denitrification filter material are respectively 30% -40%, 50% -70% and 10% -15%.

2. A preparation method of a denitrification filter material is characterized by comprising the following steps: uniformly mixing bagasse, siderite and ordinary portland cement according to a certain mass ratio to obtain a mixed material, adding water into the mixed material, uniformly mixing, granulating into balls, and then air-drying to obtain the denitrification filter material.

3. A process according to claim 2, wherein the bagasse further comprises a pre-treatment step prior to use: washing with deionized water, naturally drying at room temperature, crushing, sieving, and sieving.

4. The method according to claim 2, wherein the mass ratio of the bagasse to the siderite to the ordinary portland cement is as follows: 30% -40%: 50% -70%: 10 to 15 percent.

5. The method according to claim 2, wherein the mass ratio of water to mixed material is (60-100): 100.

6. the method of claim 2, wherein the sphere diameter d is 80 ± 20 mm.

7. The method according to claim 2, characterized in that said air-drying is preferably carried out at room temperature; and the air drying time is 5-7 days.

8. The denitrification filter material of claim 1, used for deep denitrification of tail water of sewage plants or denitrification of wastewater with low C/N ratio.

9. Use according to claim 8, wherein said wastewater with a low C/N ratio is a wastewater with a C/N ratio of less than 3.